Comparison between Different Visual Acuity Tests and Validation of a Digital Device

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Firstly, I want to congratulate the authors for their hard work and dedication to put this work together. Vision testing is a crucial part of comprehensive eye examination, and is very important to take initiatives to improve this testing system to be more systematic component in the examination process. Therefore, kudos to the team of authors for doing this tremendously useful work. Overall the manuscript is well written and engaging as well as informative a to the readers. I have some question and suggestions for the authors.

Page2 Line 80: no optical correction: you can consider this as a factor for wide range of VA, subjects with uncorrected refractive errors especially astigmatism causes great difficulty in identifying shapes and letters and it also creates confusion, and in this work you have mentioned that again the shapes were inside a box. I believe reading letters becomes easier because of the learning memory effect but shapes and symbols identification are difficult, am worried that this could be a potential reason to see the difference between the two testings (letters vs symbols).

line 72: is it only the right eye ? Did you use the dominant eye?

line 68: age 15-68: well taking a wider range is good but, this too can create a lot of bias, because of different ocular conditions like medial opacity, dry eye, contrast sensitivity, age-related changes in the retina and the eye.

line 84: add space between and/participants

Page 3: line 124: the author can consider elaborating the line ..divided by seven... not very clear to understand.

Page 4: line 145-148: Results: majority of the patient needed optical correction, so i guess my concern is same as mentioned above. And we can see in results in table 2, LEA symbol took more time than any other test, this could be because of the uncorrected refractive error (in the wide age range group)as a main component, in case the author think otherwise and explain. 

Page 6: line 176: the author can consider writing as discussion and conclusion as the title.

page 7; line 216: add space between pixelization/method and of.

line 239: add space between excellent/in.

line 239: correction needed for the citation

author can add uncorrected refractive errors and other covariates such as contrast sensitivity as limitations of the study.

general comment: there are a lot of places where there are issues with space and article use, please correct them for easy reading.

 

Author Response

Comment 1: Page2 Line 80: no optical correction: you can consider this as a factor for wide range of VA, subjects with uncorrected refractive errors especially astigmatism causes great difficulty in identifying shapes and letters and it also creates confusion, and in this work you have mentioned that again the shapes were inside a box. I believe reading letters becomes easier because of the learning memory effect but shapes and symbols identification are difficult, am worried that this could be a potential reason to see the difference between the two testings (letters vs symbols).

Response 1: Learning does not seem to be a significant factor in the identification of letters versus symbols in visual acuity testing, particularly when uncorrected refractive error is involved. Identification of any shape will depend on visual resolution ability, and when this is insufficient, learning cannot compensate for the lack of clarity.

 

Uncorrected refractive errors decrease contrast sensitivity and the resolution of fine details, which impacts the identification of any type of optotype (letters or symbols) equally.

Furthermore, in situations where letter charts, such as ETDRS, are used, the differences observed in visual acuity are more due to the intrinsic difficulty in discriminating characters due to optical deficiencies, ratherthan to familiarity with the letters.

 

 

Kalloniatis M, Luu C. Visual Acuity. In: Kolb H, Fernandez E, Nelson R, eds. Webvision: TheOrganization of the Retina and Visual System. Salt Lake City (UT): University of Utah HealthSciences Center; May 1, 2005.

Comment 2: line 72: is it only the right eye ? Did you use the dominant eye?

Response 2: The right eye was randomly selected without considering which eye is dominant for several reasons. By randomly selecting the right eye without accounting for dominance,  the procedure becomes standardized across all participants.  This helps eliminate potential bias that could arise if the dominant eye were chosen intentionally, ensuring that the results are more generalizable.

Randomly selecting the right eye assumes that any differences will be randomly distributed across participants, ensuring that ocular dominance doesn't systematically influence the outcomes. 

 

Comment 3: line 68: age 15-68: well taking a wider range is good but, this too can create a lot of bias, because of different ocular conditions like medial opacity, dry eye, contrast sensitivity, age-related changes in the retina and the eye.

Response 3: Selecting an agerange from 15 to 68 does not inherently create bias, the gradual nature of age-related conditions, combined with the fact that not all individuals experience these changes, reduces the risk of bias.  Therefore, the findings can still be generalizable across the population.

Comment 5: line 84: add space between and/participants

Response 5. We have added

Comment 6: Page 3: line 124: the author can consider elaborating the line ..divided by seven... not very clear to understand.

Response 6. Thank you for your suggestion, We have rephrased the line.

Comment 7: Page 4: line 145-148: Results: majority of the patient needed optical correction, so i guess my concern is same as mentioned above. And we can see in results in table 2, LEA symbol took more time than any other test, this could be because of the uncorrected refractive error (in the wide age range group)as a main component, in case the author think otherwise and explain. 

Response 7: Uncorrected refractive errors significantly reduce visual acuity and making it difficult for patients to identify symbols or letters. Studies show that refractive errors reduce clarity and contrast sensitivity, leading to slower response times in recognizing visual stimuli, regardless of whether the optotype is a symbol or a letter. (Kalloniatis M, Luu C. Visual Acuity. In: Kolb H, Fernandez E, Nelson R, eds. Webvision: TheOrganization of the Retina and Visual System. Salt Lake City (UT): University of Utah HealthSciences Center; May 1, 2005).

Comment 8: Page 6: line 176: the author can consider writing as discussion and conclusion as the title.

Response 8. We have added conclusión as the title.

Comment 9 . page 7; line 216: add space between pixelization/method and of.

Response 9. We have added space.

Comment 10. line 239: add space between excellent/in.

Response 10. We have added space.

Comment 11. line 239: correction needed for the citation

author can add uncorrected refractive errors and other covariates such as contrast sensitivity as limitations of the study.

general comment: there are a lot of places where there are issues with space and article use, please correct them for easy reading.

Response 11.  Thank you for your suggestion, we have solved the issues with space and article use.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This is a small sample study to compare different VA tests. The article is interesting and clear presented. However, there are several points that need clarification and revision.

1. The font size in the Bland Altman plot is too small to identified.

2. Too many tables in the result section. Consider merging several.

3. Symbols are mainly used in children and patients who do not know the letters. DIVE Symbols is a VA test like LEA Symbols. Unfortunately, children are not included in this study. Consider to include children in this study can better reflect the advantages of this VA test.

Author Response

 

Comment 1. The font size in the Bland Altman plot is too small to identified.

Response 1. Thank you, we have changed the images.

 

Comment 2. Too many tables in the result section. Consider merging several.

Response 2. Thank you for your suggestion. We have removed Table 2 because the results were already disclosed in the text.

Comment 3. Symbols are mainly used in children and patients who do not know the letters. DIVE Symbols is a VA test like LEA Symbols. Unfortunately, children are not included in this study. Consider to include children in this study can better reflect the advantages of this VA test.

Response 3. It is considered to include children in this study at a later stage. They are not have been included to avoid collaboration bias. Adults are generally more cooperative, can better follow instructions, and are less prone to variability in their responses due to factors like attention span or understanding of the task. This could lead to less reliable results and obscure the true accuracy of the test being validated.

Author Response File: Author Response.pdf